Racking mechanism for knitting machines



A. GEYER BACKING MECHANISM FOR KNITTING MACHINES Aug. 27, 1935.

Filed April 20, 1955 4 Sheets-Sheet 1 INVENTOR AQA/W GEYE/Q.

ATTORNEYS W TNESS! Aug. 27, 1935. A. GEYER 2,012,504

RACKING MECHANISM FOR KNITTING MACHINES Filed April 20, 1933 4 Sheets-Sheet 2 WITNESS.

Aug. 27, 1935. A. GEYER 2,012,504

RACKING MECHANISM FOR KNITTING MACHINES Filed April 20, 1955 4 Sheets-Sheet -:s

HNVENTOR AQA M 6 5756.

ATTORNEYS WITNESS:

Aug. 27, 1935. A. GEYER 2,012,504

" BACKING MECHANISM FOR KNITTING MACHINES Filed April 20, 1933 4 Sheets-Sheet 4 JIIIIIIHMI.

III. 5 T 7/9 iNVENTOR ADAM G'Y BY WITN E 55: Z

' ATTORNEYS Patented Aug. 27, 1935 BACKING LIECHANISM FOR KNITTING MACHINES Adam Geyer, Brooklyn, N. Y., assignor to Queens Machine Corporation, Brooklyn, N. Y., a corporation of New York Application April 20, 1933, Serial No. 666,952

V 18 Claims. (Cl. tic-69f This invention relates to new and useful improvements in knitting machines, and more particularly it pertains to a new and improved racking mechanism therefor.

needle beds or plates which are arranged in relative close, although not in contacting relation. Under control of certain mechanisms of the machine, needles are moved from one needle Bed to the other during the knittingoperation. At

intervals during the knitting operation, one of I the needle beds. is moved longitudinally with relation to the other needle bed.,' This movement of one needle bed relatively to the other needle l5 bd is known in the artas racking and it is to a novel mechanism for producing this operation, to which the present invention relates.

In most machines with which I am familiar,

the racking movement imparted to the racking needle bed is limited to a distance equal to-two,

orat" the most four needles. This has limited 7 such machines in their operation and has prevented the use bf the rack stitch in the pro--;

larged scale taken substantlally on the hne 5-5 duction of designs in the body of the fabric.

One object of the invention is to improve the construction and mode of operation of knitting machine of the afore-mentioned type and to provide suchfmachines with mechanism which will effect better and more varied knitting operations than prior machines.

A feature of the invention resides in a novel racking mechanism whereby a racking movement of any desired magnitude may be imparted to one of the needle beds A further. feature of the invention resides in a novel mechanism whereby a needle bed may be racked different distances in either direction as distinguished from prior machines in which although a needle bed may be moved a distance equal to either two or four needles during a racking movement in one direction, when racked or moved in the opposite direction, it is always returned to its initial or starting position. For example, in prior machines, if a needle bed is racked a distance equal to two needles, the next movement in' the" opposite direction has always been a distance equal to two needles, the same being true when the needle bed is racked a distance equal to four needles. k

A still further feature of the invention resides in the provision of novel mechanism whereby the various racking operations may be automatically effected, the automatic operations being controlled by pattern chains in a manner common Certain types of knitting machines employ two to selective operation of other mechanisms of such machines. I

Other features of the inventionrelate to cer,

' tain novel and improved'constructions, arrangements and combinations of parts hereinafter de-' 5 scribed and particularly pointed out in the claims, the advantages of which will be readily understood and appreciated by those skilled in the art.

The invention will be clearly understood from 10 the accompanying. drawings illustratingthe invention in its preferred form and the following detailed description of the constructions therein shown.

In the drawings, a

Figure 1 is a view in front elevation illustrating a racking mechanism constructed in accordance with the present invention,

Figure 2 is a top plan view thereof,

Figure 3 is a view in rear elevation of th racking mechanism,

Figure 4 is a view in end elevation, d

Figure 5 is a vertical sectional view on an enof Figure 2,

Figure 6 is a view similar to Figure 5 showing the parts in a different position,

Figure 7 is a horizontal sectional view taken substantially on the line 'l--'| -ofl igure 6,

Figure 8 is a vertical sectional view on an enlarged scale taken substantially on the line 8-8 of Figure 1,

Figure 9 is a detail perspective view of a portion of the mechanism, 1

Figure 10 is a vertical sectional view on an enlarged scale takensubstantially on the line l0l0 of Figure 1; and,

T Figure 11 is a detail perspective view.

In the present illustration of the invention I have not shown the needle bed since this may be of any conventional construction. In machines of this general type the needle bed has an arm which extends therefrom and by which the rack.- ing movement is imparted to the needle bed. In

the accompanying drawings'this arm is designated 20 and is shown broken away.

Various formsof mechanisms for impartingf reciprocating motion to this arm have heretofore been used. I prefer, however, to' employ a rotating" cam slotted member 2| having a cam slot 22 therein. An anti-friction roller is carried by the arm 20 0f the racking needle bedand this anti-friction roller is positioned in the cam slot 22 of the cam member 2| in such a manner that when the cam member 2| is rotated, a re- 86 bar 20.

Asbest illustratedin Figure 10, the cam member 2| may be freely mounted upon a shaft 25. This shaft is supported at one end in a bearing 26 upon the upper face of ahousing 24, the other end of the shaft being supported in the upper end of an upright arm 21. of a bracket Mi -extending from the rear of the housing 24. The shaft may be held in position in its bearingsby set screws 29. V

The housing 24 consists of a casting 30 formed on its rear face with two parallelly extending pasremovably secured to the rear of the housing by bolts or screws 31.

Carried by that end of the cam slotted member 2l which is adjacent the bearing 25, there is a gear 38 which serves the means for rotating the cam slotted member by a reciprocating rack.member 39 .mounted for'reciprocating movement in the passageway 3i. The rack member 39 has teeth 40 upon its upper edge which mesh with the teethof the gear 38 as best illustrated in Figure 6. Upon its lower edge, this rack member is cutout as at 4| and in said out out portion 4! there are rack teeth 42 which/ mesh with a gear 43 mounted in the cut out portion 34 0f the web 33 and keyed or otherwise secured to a shaft 44 mounted in the housing 24. The rear end of this shaft 44 projects beyond the housing 24 and secured thereto there are'two toothed wheels 45 and 45 which are engaged respectively by holding dogs 41 and 48 carried respectively by levers 49 and 50 pivotally mounted upon the rear wall-of the housing as at 5|. A spring such as 52 is attached at one end toeach'of said levers 49 and 50, the other end of said springs being connected as at 53 to the housing 24. By this construction the shaft 44 and the gear 43 are held against movement except when operated by the operating mechanism of the machine, The teeth of the two wheels 45, and 45, are disposed in opposite directions in order that the cam slotted member may be held against movement in either direction. I

The reference numeral 55 designates a rack bar which is slidably mounted in the passageway 32.

' The upper edge of this rack bar is cut out as at right in Figure 6, this being accomplished through the gear 43 which meshes with the teeth of the rack memb'ers39 and 55. On the other hand,

when the rack,member 55 is movedto the left in Figure 6, the rack member 39 will be moved to the right in said figure and the cam slotted member 2| will be rotated in a counter-clockwise direction. These movements of the cam slotted member 2i in' either the clockwise or counterclockwise direction will impart racking movement in opposite directions to the arm 20 of the racking needle bed.

The rack member 39 is moved to the left in ciprocating movement will be imparted ,to the Figure 6 by a reciprocable power transmitting member fiflfand the rack member 55 is moved to the left in said figure by a reciprocable power transmitting member 61. These power transmitting members and BI have right angular extensions 62 and 63 respectively which engage respectively, the rack bars 39 and 55 to push them to the left in Figure 6 in the manner heretofore described. The power transmitting mem' ber 60 is cut' out as at 64 and in said out out portion 64, a series of rack teeth 66 are formed.

The power transmitting member BI is likewise cut out at 61 and formed with rack teeth 68 I and interposed between the power transmitting members and having engagement wth the rack teeth 66 and 58, there is a gear 59 carried upon a bolt or the like 13.

The power transmitting members 68 and (ii are slidably mounted in a housing H and the bolt 10 upon which the gear 69 is carried is mounted in one of the side walls of this housing 1 l Interposed between the power transmitting members 60 and 6!, there is an anti-friction bearing 12 mounted in a recess 13, preferably in the power transmitting member 6|, this anti-friction hearing being mounted upon a shaft 14.

Referring to Figure 5 it will be n'otedthat each power transmitting member is providedupon its right-hand end with an angular extension, these extensions being designated 15 and 16 respectively. The angular extension 15 of the power transmitting member 53 is stepped along one edge to provide a plurality of faces 15 15 15, 15, 15, 15, 15 15 15 15 15 I5 15 and 15.

' The angular extension of the power transmitting member Si is likewise stepped to provide a plurality of faces 16, 15, 16, 76 16, 16?, 16 75,

be connected by a link i9 with the power of the machine in any desired manner. It may, if desired, be continuously operating, or it 'may be intermittently'operated only'at such. times as a. racking operation is desired, but in either instance the reciprocating power member 11 e preferably moves, or operates through a stroke of fixed length.

I wi1l now proceed to describe the operation out its entire stroke without eifecting any oper- 'at'on of the mechanism.

To effect a racking mechanism with the parts in the position shown in Figure 5 it will be necessary to elevate the power transmitting member 6| so that one of the faces formed on the angu'-' lar member 16 will be raised into the path of travel of the power driving member IT. For example, lets assume that the power transmitting device GI has been elevated to the position in which it is shown in full lines in Figurefi. In

this position, the reciprocating power driving 'rnember'will engage the 'face l6 as it nears the completion of its inward stroke in said figure. When the power driving member I? engages the face of the a ular member 15 the power left in said Figure 6 and will through the medium of its right angular extension 63, move the reciprocating rack member 55 to the left. Movement of this member to the left will drive the gear 43 in a clockwise direction moving the rack member 39 to the right and rotating the cam slotted member 2| in a counter-clockwise direction and reciprocating the bar 20. Movement of the rack member 39 to the right causes movement of the power transmitting member 60 to the right and at the end of the stroke of the power driving member 11 the face I of the angular extension I5 will engage the power driving member I7 which in turn acts as a stop to prevent further movement of the power transmitting member 60 to the right.

The needle bed having been racked in the above described manner, to return the same to the neutral position the power transmitting members are lowered so that the face I5 of the angular extension I5 will be engaged by the power driving member and moved to the left (This movement of the power transmitting member 60 to the left will move the cam-slotted member 2| in a clockwise direction thus imparting a reciprocating movement to the bar 20 in a direction opposite to that above described. Movement of the rack member 39 to the left causes a movement of the rack member 55 to the right through the medium of the gear 43 and the rack member 55 in moving to the right will move the power transmitting member 6| to the right so that the power transmitting members 60 and 6I will assume the position in which they are shown in Figure 5 at the end of the stroke of the power driving member 11. As the power transmitting member 6| is moved to the right,

' the face 16 of the angular extension I6 will engage the power driving member 11, which acts as a stop to prevent further movement of the power transmitting member 6| to the right.

The faces on the angular extensions of the 7 power transmitting members are so arranged that the offset therebetween will be equal to the distance'between single needles in the needle beds and by adjustment of the power transmitting members, a movement which will rack the racking needle bed, one needle or more may be had. -The right angular extensions 62 and 63 of the power transmitting members 60 and 6| respectively are provided so that the rack members 39 and 55 may be operated by the power transmitting members regardless'of the elevated position of the latter.

Means is provided for adjusting the power transmitting members 60 and BI relative to the power driving member 11. In the present embodiment of the invention this adjustment is effected by vertical movement of the power transmitting members 60 and BI and to this end the housing II in which the power transmitting members are carried is mounted for vertical sliding movement between two guides 80 and 0| Q the guides being hollowed out or provided with channels 82 and 83 respectively, in which the housing II is mounted for sliding movement.

Projecting from the guide member 8| there is a stud 90 and pivotally mounted as at9|"upon said stud there is a lever 92. This lever 92 is adapted to rock about its pivot point 9| and pivotally connected as at 93 to its free end there is a link 94 provided with an open eye 95. ,Pivotallymounted as at 96 there is a lever 9l. One end of this lever 91 carries a pin '98 which op- Thisroller is adapted to ride upon and actuate a cam member I00 which is mounted upon a lever IOI pivotally mounted to the guide 8| as at I02. Pivotally connected to the lever IOI .as at I03 there is a link I04 and this link I04 is pivotally connected as at I05 to a lever I06. This lever I06 is pivotally mounted as at I01 and pivotally connected as at I08 to the free end of said lever I06 there is a link I09. As best illustrated in Figure 8, this link I09 is pivotally attached to a stud I I0 which in turn is connected as at III to the housing II in which the power transmitting members 60 and 6| are carried. The stud IIO travels'in a slot H2 in the front guide BI and in travelling through said' slot II 2 the stud I'I0 serves to raise the housing 1|. When the housing II is in an elevated position it will move by gravity to a lower position if permitted, its movement from elevated positions to lowered positions being checked by a spring I5, see Figure 1. ment of the housing 'II is guided by a gear 3 which meshes with a rack 4 carried by the housing 'II. v

With the parts in the position inwhich they are shown in Figure 1, it is obvious that if the The vertical move- 1 free end of the lever 92 be elevated, the link 94 will rock the lever 91 about its pivotal point 96. This will cause the roller 99 to depress the lever IOI and this lever through the link I04 will rock the lever"I06 about its pivotalpoint I0'I, raising the link I09. Raising the link I09 will elevate the stud |I0 consequently raising the housing II.

The lever 92 may be rocked about its pivotal 7 point in any desired manner.

I prefer, however, 7

to use a plurality of pattern chains having links H9 and |20.- The sprocket H9 is carried upon a shaft |2I which extends through the base portion of the guides 80 and 8|. The sprocket I20 is carried by a hollow shaft or sleeve I22 which surrounds the shaft |2I and which also extends through the base portion of the guides 80 and 8|. On its opposite end, the shaft I2| has keyed thereto a toothed ratchet I25 and adjacent the toothed ratchet I25 there is a toothed ratchet I26 which is keyed to the sleeve I22. iSuitable driving means for the toothed ratchets I25 and I28 is provided and this driving means consists of a plurality of reciprocating dogs which engage the teeth of the ratchets I25and I26 and cause rotation of the shaft or sleeve in a step by step movement. Rotation of the shaft I2| or sleeve I22 causes a rotation of their respective sprocket wheels and this will move the chains II! to bring the links II8 thereof beneath the rollers H5 or II6 as the case may be to effect an operation of the lever 92 to raise or permit of lowering of the housing I I.

operaterespectively the ratchets I25 and I26 are supported upon pivoted levers I30 and I3I' respectively, These pivoted levers are notched atdifierent locations as at I32 and a pivoted lever I33 has rollers I34 which engage the levers I30 and I 3| to hold-them elevated and the dogs I28 and I29 out of contact with the ratchets I25 75 The two dogs I28 and I29 which,

as best illustrated in Figure 3.

may be rocked about its pivotal point by a suitat I35 upon the outer face of the rear guide The lever I33 of the lever I3I this lever I3I will be rocked about the pivotal point I31 and will lower its dog I28 into engagement with the driving ratchet I26. It is intended that the dogs I28 and I29,

will'be continuously operated in such a manner that immediately they are lowered into engagement with their driving ratchet an operation thereof will be had. The driving ratchets I25 and I26 areheld' against accidental operation by means of holding pawls or dogs I40 and I which are held in engagement with their respective ratchets by coil springs I42 and I43 respectively. I

A complete operation of the device will now be given.

With the parts in the neutral position in which "they are shown in Figure 1 the anti-friction roller 23 of the arm 20 will be positioned at the left hand end of the cam slot 22 in Figure 2. The housing II will be at the bottom-of the guides and the chains III and *8 will be so positioned that the low link of each will be beneath the rollers H5 and IIB.

In this position the power driving member I! in its reciprocating movement will move to the left in Figure 5 and will engage the face 15 of the angular extension I5 and-the face 16 of the angular extension I6. These faces I5 and 16 in the neutral position are located exactly at the end of the stroke of the power driving member I1 and consequently no moyement of the power transmitting members 60 and SI is had.

The several pattern chains are so arranged that they will be driven to produce a racking movement or the desired extent at the desired time.. For the sake of illustration let us assume that the pattern chain II 'I;has been driven by' its sprocket H9 to a position where its second lowest link has passed beneath the roller H5. The second lowest link in passing beneath the roller II5 .will rock the lever 92 and elevate the housing 1| as heretofore described. This elevation of the housing II will elevate the power transmitting members 60 and BI. to a position where the face I6 of the angular extension It will be engaged by the power driving member upon its next stroke to the left in Figure 5, just before the end of the stroke. As the power driving member engages the face 16* the power transmittingmember 6| is moved to the left in Figure 5 and through the medium of the rack members 55 and 39 the cam slotted member 2I will be.

right in Figure 5. In this position the power v 2,012,504- and I26. This lever I33 is pivotallymounted as driving member is free to reciprocate without further operation of the mechanism since the faces I5 and I6 will be at the end of the stroke of the power driving member 11.

If, now, it be desired to produce a further racking operation of the needle bed, the pattern chain will be so made up that immediately 'following the second lowest link there would be a higher 1 link in order that the housing II may be still further elevated tomove one 'of the faces of the angular extension I6 of the power transmitting member 6| into the path of the power driving member I! which-would produce a further racking operation in the manner above described when the face of the angular extension I6 is engaged by the reciprocating power member. If, on the other hand, it be desired to return the racked needle bed to the 'neutral position the next link in the chain would be any of the lowest links. This link when it passed beneath the roller I I5 would permit the housing II to move downwardly under the action of gravity and position the face I5 of the angular extension I5 in the path of the reciprocating power member 'I'I. When the reciprocating power member 17 moves to the left in Figure 5 it will engage the face 15*, move the power transmitting member 60 to the left, operating the rack member 39 to rotate the cam slotted member 2I in a clockwise direction and return the anti-friction roller 23 to the left hand end of. the cam slot 22 in Figure 2 returning the rackedneedle bed to the neutral position. v

From the foregoing it will be apparent that the mechanism may be so' controlled by pattern chains to produce a rack stick at any desired time and that the racking needle bed may be moved any desired distance merely by varying the height of the links of the pattern chains and thereby raising and lowering the housing and power transmitting members to properly position their angular extensions with respect tothe power driving member.

While the invention has been herein "presented in a preferred, form, it is to be understood that it is not limitedto the construction herein shown and that it may be embodied in other forms withoutdepafrting from the 'scope thereof.

Having thus described the invention, what is claimed as new and what it is desired to secure by Letters Patent of the United States, is:

1. A mechanism of the class described includ ing a reciprocatingneedle bed, a rotary member for imparting reciprocatingmovement to said reciprocating needle bed, reciprocating means including driving and operating members for imparting rotary motion to said rotary member, an adjustable stop'ofor limiting the reciprocal movement of said operating member, thereby to determine the extent of racking movement imparted to the reciprocating needle bed, and means controlled by said reciprocating means for operating said adjustable stop.

2. A mechanism of the class described including a reciprocating needle bed, a rotary member for imparting reciprocating movement to said reciprocating needle bed, reciprocating means including driving and operating members for imparting rotary motion to said rotary member, a selectively adjustable stop for limiting the reciprocal movement of said operating member, thereby to determine the extent' of racking movement imparted to the reciprocating needle bed, and means controlled by said reciprocating means for operating said adjustable stop.

3. In aknitting machine, aracking mechanismtioned means into the path of travel of said including a reciprocating driving. member and a racking mechanism operated thereby, said racking mechanism includinga reciprocating member and a stop, the reciprocating member being operated by the reciprocating driving member, and the stop being movable into engagement with the reciprocating driving member by said reciprocating member, thereby to limit the racking movement of the racking mechanism.

4. In a knitting machine, a racking mechanism including a reciprocating driving member having a stroke of fixed magnitude, a reciprocating operating member for eifecting a racking operation, a reciprocating stop for limiting the extent of racking movement, and means for moving said reciprocating operating member and said step into the path of the reciprocating driving member at difierent positions in the stroke thereof.

5. In a knitting machine, a racking mechanism including a reciprocating driving member, a re ciprocating member movable into the path of travel of said reciprocating driving member to efiect a reciprocating movement of the reciprocating member by. the reciprocating driving member, a racking needle bed, means for imparting racking. movement to said nedle bed from said reciprocating member when it is operated by the reciprocating driving member, and means for limiting the extent of racking movement imparted to the racking needle bed.

6. In a knitting machine, a racking mechanism including a reciprocating driving member, a reciprocating member movable into the path of travel of said reciprocating driving member to effect a reciprocating movement of the reciprocating member by the reciprocating driving member a racking needle bed, means for imparting racking movement to said needle bed from said reciprocating memberwhenjt is op-' erated by the reciprocating driving member, and means .for limiting the extent of racking movement imparted to the racking needle bed, said last mentioned means including a member movable into engagement with said reciprocating driving member.

7. In a knitting machine, a racking mechanism including a reciprocating driving member having a .stroke of predetermined length, a racking needle bed, and means for imparting a racking movement to said racking needle bed, the last mentioned means including a reciprocative -member movable into the path of travel of the reciprocating driving member at different points in .the stroke thereof.

8. A racking mechanism for knitting machines comprising in combination, a racking needle bed, and means "for imparting a racking movement thereto, the last mentioned means including a reciprocating driving member, a rotary cam member, a rack and gear for imparting rotary motion to said cam member, and means operated by said reciprocatingdriving member for imparting differentdegrees of racking movement to said rotating cam member.

9. A racking mechanism for knitting machines comprising in combination, a racking needle bed and means for imparting a racking movement thereto, said last mentioned means including a reciprocating \driving member, a rotary cam member, means interposed between the reciprocating driving member and the rotary cam member for transmitting power from said reciprocating driving member to said rotary cam member, and'means for introducing-said 'last menmember.

reciprocating driving means at different points in the stroke thereof, whereby to impart difierent degrees of racking movement to the rotary cam '10. A racking mechanism for knitting machines comprising in combination, a racking needle bed and means for imparting a racking movement thereto, the last mentioned means including a reciprocating driving member, a rotary cam member, means interposed between the reciprocating driving member and the rotary cam member for transmitting power from said reciprocating driving member to said rotary cam member, andfmeans for introducing said last mentioned means into the path of travel of said reciprocating driving means at diiferent points in the strokethereof, whereby to impart difierent degrees of racking. movement to the rotary cam member, and means for automatically determining the position of the power transmitting means relative to the reciprocating driving member. 11. A racking mechanism for knitting machines comprising in combination, a racking needle bed, a rotary cam slotted member for imparting a racking movement to said racking needle bed, and means for driving said rotary cam slotted member in opposite directions to effect operation of the racking needle bed in opposite directions, the last mentioned means including a plurality of intergeared rack members, means for gearing oneof said rack members to said rotating cam slotted member, a plurality of intergeared power transmitting members for imparting motion to said rack members, and driving means for selectively and singly engaging said power transmitting members to selectively operate said rack members.

12. liracking mechanism for knitting machines comprising in combination, a racking needle bed, a rotary cam for imparting a racking movement to said racking needle bed, and means for driving said rotary cam member in opposite directions to efiect operation of the racking needle bed in opposite directions, the,last mentioned means including a plurality of intergeared rack members, means for gearing one of said rack members to said rotating cam slotted member, a pair of intergeared power transmitting members for imparting motion to said rack members, a reciprocating driving means, and means for moving said power transmitting members singly into operative engagement with said driving means.

13. A racking mechanism for knitting machines comprising in combination, aracking needle bed, a rotary cam for imparting a racking movement to said racking needle bed, and means for driving'said rotary cam, member in oppositedirections to eflect operation of the racking needle bed in opposite directions, the last mentioned means including a plurality of intergeared rack mempositions, without being first racked to said normal position, and a stop member actuated by said operating member to engage said driving member to limit the racking movement of said bed.

16. In a knitting machine, aneedle bed, a rack- I ing mechanism therefor including a reciprocatory driving member having a stroke of constant length, a reciprocatory operating member for said needle bed having movements, of different length and actuated-by said driving member, a reeiprocatory stop member for limitingthe extent of movement of said operating member, and means to effect relative adjustments between saiddriving and operating members to vary the length of movements of the latter to therebychange the degree of racking of said needle bed,

2,012,564 needle bed, and an adjustable stop actuated by 17. In. a knitting machine, a needle bed, a racking mechanism therefor including a reciprocatory driving member having a stroke of constant length, a reciprocatory operating member for said needle bed having movements of different length and actuated by said driving member, a

. reciprocatory stop member for limiting the extent of movement of said operating member, a rotary member responsive to the varied reciprocating movements of said operating member for racking said needle bed, and meansto efiect relative adjustments between said driving and operating members to vary the amount of reciprocation of the latter to thereby alter the degree of rotation of said rotary member. i

r 18. In a knitting machine, a needle bed, a rack-. ing mechanism therefor includinga driving memher, an operating member responsive to said driving member to rack said bed and having a stepped formation providing a series of faces operatively associated with said driving member, a stop member actuated by said operating member and also having a stepped formation providing a series of contacting faces each of which forms a stop which cooperates with said driving member to limitthe racking movement of said needle bed.

GEYER. 

